Recently, along with tendency toward large scale in capacity of recording medium such as rewritable optical disks, etc. and with improvement in techniques for compressing moving pictures, the techniques for digital cameras and recordable players, etc. that have the function of recording moving pictures on optical disks have been reviewed. Under the situation, recordings of both moving and still pictures on optical disks in a common format have coming into reality.
As such a compression method, it would be advantageous to use the MPEG (Moving Picture Expert Group) standard for recording moving pictures from the viewpoint of compression efficiency. The MPEG standard is a well-known technique described in, for example, “The Latest Guidebook to MPEG” (ASCII Co., Ltd., Aug. 1, 1994), etc. The detailed description for the MPEG will thus be omitted here.
As for a compression method for still pictures, the JPEG (Joint Photographic coding Experts Group) standard used for recording digital still pictures from general electronic still cameras may be replaced with another method if the method can record the data equivalent to one frame of moving pictures recorded by the MPEG as I picture. If the recordable player described above has a means for expanding pictures compressed by, for example, the MPEG compression method, and then both moving and still pictures can be reproduced. In this case, it is no need to use such an expanding means as JPEG for reproducing pictures, thereby the cost of the reproducing system can be reduced.
However, the data must be processed fast to encode moving pictures in real time and it is impossible to increase the number of pixels per frame of moving pictures so much. For example, the maximum number of pixels per frame is 720 in the horizontal direction and 480 in the vertical direction on the encoding level referred to as the main profile main level which handles the resolution of the present TV sets, required for the MPEG method. On the other hand, the encoding time for one sheet of still pictures is not limited so strictly, so that the number of pixels to be handled in accordance with the high resolution of the object photographing element can be increased. Consequently, most of the present electronic still cameras can record still pictures with the use of the JPEG compression method and the number of pixels to be handled by those cameras is being increased year after year.
In order to enable any reproducing apparatus such as recordable players and ordinary players to reproduce data on the basis of the MPEG, as well as record high resolution still pictures, it is only needed to record both MPEG I pictures and JPEG file pictures. Such techniques are disclosed in, for example, the Japanese Patent Unexamined Publication No. 10-108133. According to the disclosed techniques, pictures is encoded and recorded with a plurality of different methods at a time and both moving and still pictures are encoded and recorded simultaneously. The conventional techniques, however, do not consider encoding of still pictures read from a fine photographing element with the use of such an encoding method as MPEG for moving pictures. In particular, no care is paid for the difference in reading pictures from a photographing element between reading fine still pictures and reading moving pictures.
Furthermore, the above conventional techniques do not consider any correspondence to recordings of both moving and still pictures, although they can record both encoded still pictures and partial still pictures so as to make it easier for an user to control the apparatus, for example, for searching pictures when in reproducing.